1859.] on the Gorilla. 17 



the first set is shed. If a young gorilla, chimpanzee, or orang, be 

 compared with a young siamang, of corresponding age, the absolutely 

 larger size and better shape of brain, the deeper and more numerous 

 convolutions of the cerebrum, and the more completely covered cere- 

 bellum, unequivocally demonstrate the higiier organization of the 

 shorter-armed apes ; " in the structure of the brain," writes Vrolik,* 

 in accordance with all other comparative anatomists, " they " (chim- 

 panzee and orang-utan) *' approach the nearest to man." The degree 

 to which the chimpanzee and orang so resembled the human type 

 seemed much closer to Cuvier, who knew those great apes only in 

 their immaturity, with their small milk teeth and precociously de- 

 veloped brain. Accordingly, the anthropoid characters of the Simia 

 satyrus and Simia troglodytes, as deduced from the facial angle and 

 dentition, are proportionally exaggerated in the " Regne Animal.'*! 

 As growth proceeds, the milk-teeth are shed, the jaws expand, the 

 great canines succeed their diminutive representatives, the biting 

 muscles gain a proportional increase of carneous fibres, their bony 

 fulcra respond to the call for increased surface of attachment, tlie 

 sagittal and occipital crests begin to rise ; but the brain grows no 

 more ; its cranial box retains the size it showed in immaturity ; it 

 finally becomes masked by the superinduced osseous developments in 

 those apes which attain the largest stature and wield the most for- 

 midably armed jaws. Yet under this disguise of physical force, the 

 brain is still the better and the larger than is that of the little long- 

 armed ape, wiiich retains throughout life so much more of the characters 

 of immaturity, especially in the structure of the skull. 



The siamang and other gibbons have smaller lower but longer 

 upper canines, relatively, than in the orangs and chimpanzees ; the 

 permanent ones more quickly attain their full size, and are sooner in 

 their place in the jaws ; consequently the last molar teeth — what we 

 call the " wisdom-teeth " — come last into place as they do in the 

 human species. But, if this be interpreted as of importance in deter- 

 mining the relative affinity of the longer-armed and shorter-armed 

 apes to man, it is a character in which, as in their seeming superior 

 cerebral development, the Hylohates agree with some much lower 

 quadrumana with still snjaller canines. The comparative anatomist, 

 pursuing this most inte'esting comparison with clear knowledge of the 

 true conditions and significance of a globular cranium and small jaws 

 within the quadrumanous order, turns his attention to the true dis- 

 tinctive characters of the human organization. 



In respect to the brain, he would look not so much for its relative 

 size to the body, as for its relative size in the species compared one 

 with another in the same natural group. Pie would enquire what 

 quadrumanous animal shows absolutely the biggest brain ? what species 

 shows the deepest and most numerous and winding convolutions ? in 



* Art. Quadrumana, CyclopaDdia of Anatomy, vol. iv., p. 195. 

 t Ed. 1829, pp.87, 89. 



Vol. ^I. (No. 29.) c 



